A master/slave manipulator is recently receiving attention since an operator can carry out a slave operation of a slave manipulator (hereinafter referred to as a slave) by operating a master manipulator (hereinafter referred to as a master). In the master/slave manipulators, there are master/slave manipulators with a non-similar construction in which the forms of a master 1 and a slave 2 are not similar as illustrated in FIGS. 19A and 19B. The master/slave manipulators with a non-similar construction have an advantage of being capable of dealing with various kinds of operations, since the constructions and specifications of the master 1 and slave 2 can be properly selected according to the nature of an operation and the intentions of an operator.
However, in most of the above-described master/slave manipulators with a non-similar construction, an operating area A of a leading end 11 of the master 1 and a working area B of a leading end 21 of the slave 2 are not similar, as FIGS. 19A and 19B illustrate. Therefore, as FIG. 19C illustrates, when an area A', which is the similarly enlarged operating area A, is to be brought into correspondence with the working area B, the boundaries do not match and part of the areas extends off. The master/slave manipulators having the above-described areas A and B have the following disadvantages.
(1) In the areas like the areas Aa and Ab (diagonally shaded hatching portions), which the leading end 21 of the slave 2 cannot reach, the slave 2 does not follow the master 1 even if the master 1 is operated.
(2) The leading end 21 of the slave 2 following the master 1 cannot reach the areas like the areas Ba and Bb (vertically shaded hatching portions), which the leading end 11 of the master 1 cannot reach. Specifically, the leading end 21 of the slave 2 can be operated only in the area other than the areas Ba and Bb in the basic operating area B.
Depending on settings by a design engineer, the following disadvantages may be caused.
(3) Even if an operation prohibited area BB (the working area B+the operation prohibited area BB=a slave movable area) is set for the leading end 21 of the slave 2 for various reasons, in the case that the operating area A of the leading end 11 of the master 1 is overlaid on the area BB, if the master 1 is operated, the slave 2 operates even though the leading end 21 of the slave 2 is in the operation prohibited area BB.
Specifically, common operating area of the master 1 and the slave 2 becomes small, therefore disadvantages of a reduced operating capability, worsened operability, and increasing dangers are caused.
Naturally, by bringing the working amounts .beta.1 and .beta.2 of each degree of freedom of the master 1 in a one-to-one correspondence with the working amounts .theta.1 and .theta.2 of each degree of freedom of the slave 2, the entire operating area A is brought into correspondence with the entire working area B, and the above-described common operating area can be at its maximum. However, a concrete corresponding relationship between the degrees of freedom of the master 1 and the slave 2 is at a linear correspondence level, and no corresponding relationship with a special meaning is given (for example, Japanese Patent Application Laid-open No. 2-145272).
Here, disadvantages in a case of linear correspondence is specifically described. For example, in a linear correspondence in FIGS. 19A and 19B, the working amount (for example, a rotary working amount .theta.1 of a first axis of the slave 2 is brought in a linear correspondence with the working amount (for example, a rotary working amount) .beta.1 of a first axis of the master 1 and the rotary working amount .theta.2 of a second axis of the slave 2 is brought in a linear correspondence with the rotary working amount .beta.2 of a second axis of the master 1, as illustrated in FIGS. 20A and 20B. However, in a simple correspondence like this, as FIGS. 21A and 21B illustrate, when the leading end 11 of the master 1 is moved along circular arcs M1 and M2, the leading end 21 of the slave 2 moves along circular arcs S1 and S2, so that the leading end 21 of the slave 2 moves in a direction different from the direction in which the leading end 11 of the master 1 operates. Specifically, in the entire area of the working area B of the slave 2, an operator is given a sense of incongruity.
The command transfer system of a master/slave manipulator of another conventional art is described with reference to FIGS. 22 to 26B. The command transfer system in FIG. 22 is constructed by interposing a second comparator 13, a gain multiplier 14, and an actuator 15 between the master 1 for operation and the slave 2 for working, from the master 1 to the slave 2 in the order described, and by providing a feedback circuit between the slave 2 to the second comparator 13 from the slave 2 to the second comparator 13, and control is carried out so that the slave 2 moves following the attitude of the master 1.
To this end, a deviation .sigma. is obtained by comparing the attitude information (for example, an angle detected in an angle detecting device 1a) .theta.m of the master 1 to the attitude information (for example, an angle detected in an angle detecting device 2a) .theta.s of the slave 2 in the second comparator 13. A gain G is applied to the deviation .sigma. in the gain multiplier 14, and the result is inputted to the actuator 15 of the slave 2 to operate the slave 2 in a direction to make the deviation .sigma. to be zero. Specifically, the attitude information .theta.s is controlled so as to conform to the attitude information .theta.m. This is expressed in the following equation (1) EQU .theta.s.fwdarw..theta.m (1)
More specifically, in the command transfer system in FIG. 22, as FIGS. 24A and 24B illustrate, the slave 2 is controlled so as to have an attitude and enlargement ratio in a fixed correspondence with the master 1. Therefore, in an actual manipulator operation, it is often convenient if the corresponding relationship between the master 1 and the slave 2 can be controlled according to the requirements of an operator, for example, as follows.
As FIGS. 25A and 25B illustrate, if corresponding positions of the leading ends of the master 1 and slave 2 can be shifted, an operator can operate the master 1 in a position in which the leading end of the master 1 is operated most easily, and contribution to a reduced load in operation and a safe operation can be made.
Further, as FIGS. 26A and 26B illustrate, if an enlargement ratio in a corresponding position area of the leading end of the slave 2 to the leading end of the master 1 is changeable, the enlargement ratio can be changed to a large enlargement ratio when an operation is to be carried out at high speed, and the enlargement ratio can be changed to a small enlargement ratio when an operation is to be carried out with precision, therefore the operations can be conducted in a wider range.
Then, the command transfer system in FIG. 23 is cited as a system for achieving corresponding position shift and enlargement ratio change of the master 1 and the slave 2 in the above-described two examples. This transfer system can further input reference attitude information .theta.mo by interposing a first comparator 7a, an enlargement ratio multiplier 16, and an adder 7b between the master 1 and the second comparator 13, from the master 1 to the second comparator 13 of the command transfer system in FIG. 22 in the order described. In this command transfer system, the attitude information .theta.s is controlled so as to correspond to an altered attitude information .theta.m1 outputted from the adder 7b. This is expressed by the following equation (2). EQU .theta.s.fwdarw..theta.m1 (2)
The altered attitude information .theta.m1 is shown by the following equation (3), as understood from the first comparator 7a, the enlargement ratio multiplier 16 and the adder 7b in FIG. 23. EQU .theta.m1=(.theta.m-.theta.mo).times.r+.theta.mo (3)
Here, r is an enlargement ratio. Specifically, by giving the reference attitude information .theta.mo of ".theta.m=.theta.s=.theta.mo", the enlargement ratio r can be changed at will.
However, the change of the enlargement ratio r of the master 1 and the slave 2 in the command transfer system in FIG. 23 is not preferable for safety reasons since the altered attitude information .theta.m1 is varied and the slave 2 is moved until the reference attitude information .theta.mo which is ".theta.s=.theta.mo" is set. There are several disadvantages, for example, a disadvantage of having to adjust both of the reference attitude information .theta.mo and the enlargement ratio r in order to respectively set the master 1 and the slave 2 in an arbitrary attitude (in other words, in order to shift a corresponding position).
FIG. 27 is a diagram of a bilateral type of master/slave manipulator command transfer system, and the master 1 is provided with an attitude and force detector 1c and an actuator 1b, while the slave 2 is provided with an attitude and force detector 2c and an actuator 2b. Between the master 1 and the slave 2, a control means 30A, which is equipped with a master following command value operation section 31 and a reaction force calculating operation section 32 and which consists of, for example, a microcomputer, is provided. The master following command value operation section 31 inputs an attitude .theta.m3 and an operation force Fmo from the attitude and force detector 1c while inputting an attitude .theta.s3 of the slave 2 from the attitude and force detector 2c, then computing a command y from the attitude .theta.m3, operation force Fmo and the attitude .theta.s3, and outputs this command y to the actuator 2b. The actuator 2b operates the slave 2 correspondingly to this command y. Thereby when the operator operates the master 1, the slave 2 operates following the master 1.
On the other hand, the reaction force calculating operation section 32 inputs a load Fx of the slave 2 from the attitude and force detector 2c, and a reaction force command value ym, to which a specified multiplied factor is applied, is outputted to the actuator 1b. Here, the load Fx is an added value of the tare of the slave 2 with an attachment and the force which the slave 2 gives to the outside. The actuator 1b gives a reaction force corresponding to the reaction force command value ym. For example, in a master/slave manipulator which generates a large load Fx, a reaction force of one several tenth to one several hundredth of the load Fx is returned to the master 1, so that an operator can carry out operations while feeling the condition of the load of the slave 2 by this reaction force. A unilateral type of master/slave manipulator has the above-described construction from which the actuator 1b and the reaction force calculating operation section 32 are omitted, so that an operator cannot feel the condition of the load.
However, by the above-described conventional manipulator, operations can be carried out with an working force larger than human power, but the following disadvantages exist. FIG. 28 is a view of a wheeled rotary type of master/slave manipulator , and a grinder 18 is attached at the leading end of the slave 2 as an attachment. Since the manipulator is made so as to exert the effect of a large working force, a large load can be easily encountered, but the load which is transferred to the operator is so small that the operator cannot feel the load. Accordingly, when a surface of a workpiece 19 is to be precisely cut, an operator can obtain only a small reaction force with a bilateral type; and a reaction force cannot be obtained with a unilateral type, therefore there is a disadvantage of being unable to conduct a precise operation such as a precise cutting with a working force being precisely adjusted.
The above-described operation can be seen not only in a grinder operation but also in an operation of holding a fragile object. More specifically, the conventional manipulators have a disadvantage of being unable to be preferably used for operations requiring precise adjustment of a working force such as a tensile force, pressing force, holding force, or the like.